Yes, I sent a couple with 3-4 moderate/major updates each. I think they helped a lot because in addition to demonstrating sustained interest, they addressed weaknesses from my undergrad and previous application beyond the improvements I demonstrated in my AMCAS and secondary.
First update letter (early December 2023):
- Thanked CWRU for the interview, mentioning interviewers by name (I also sent them thank-you letters through the portal)
- Took on new responsibilities at a free clinic (patient intake)
- Did very well (A+ final grade) in a postbac neuroscience course at a nearby state university and sent the transcript when that became available the following week - this was particularly helpful, as I didn't really know how to study for biology/biochemistry until after I finished my bachelor's and it kinda showed in my sGPA
- Was selected for an oral presentation at a conference and was awarded a travel scholarship
- Reiterated my interest in CWRU
Second update letter (mid-May 2024; two days before I got the call)
- Reiterated my strong interest
- Gained shadowing experience by attending Grand Rounds in two specialties at my institution (a premier research hospital, so lots of rare conditions and emphasis on research)
- Presented another poster (my fifth)
- Submitted two manuscripts for peer review and publication (1 first-author, 1 mid-author)
- Thanked them for their continued interest in my application, said CWRU was my top choice (which is true), and discussed how I hope to contribute, including through research (mentioning a PI by name and why I am interested in working with him based on my existing research experience)
The big thing to remember with update letters is that it isn't enough to just say "I did all these cool things" - you also have to mention what you got out of it, how you contributed, and how it works toward your goal. For instance, with the free clinic work, I talked about how I learned more clinical skills and improved my Spanish while meeting a volunteer need for the clinic and developing my ability to work with diverse and underserved patient populations.